﻿<p>A feature element is a generalization of all existence
dependent elements which modify the shape and appearance of the
associated master element. The <em>IfcFeatureElement</em> offers
the ability to handle shape modifiers as semantic objects within
the IFC object model.</p>
<blockquote class="note">
NOTE&nbsp; The term "feature" has a predefined meaning in a
context of "feature-based modeling" and within steel construction
work. It is introduced here in a broader sense to cover all
existence dependent, but semantically described, modifiers of an
element's shape and appearance. It is envisioned that future
releases enhance the feature-based capabilities of the IFC
model.
</blockquote>

<p>In contrary to the aggregation, as used in
<em>IfcElementAssembly</em>, that defines the aggregate as a
container element, that has equally treated parts, the feature
concept introduced by <em>IfcFeatureElement</em> defines the master
element with subordinate parts as additions, or with voids or
cut-outs as subtractions.</p>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC2x2.
</blockquote>
<blockquote class="change-ifc2x2">
IFC2x2 CHANGE&nbsp; The entity is introduced as an upward compatible extension of the IFC2x platform. It is an
intermediate abstract supertype without defining its own explicit
attributes.
</blockquote>